Math Equation question

[Epic DaVinci]

Hi All,

After recently watching HOC's new series, i watched where he worked out some equations relating to calculating DV.

My question is, if i was given such an equation to work out, how would i know what units to use as the numbers to input?

For instance: F=M/A where it comes to adding the Mass, how do i know weather its in Kilos, Tons, Pounds, Ounces etc etc...

because based on what unit i use, can it seriously affect the result?

Edited July 16, 2013 by Epic DaVinci
fixing bad typing

[maltesh]

In the simulation of Kerbal Space program, 1 Force unit of thrust / 1 Mass unit = 1 m/s² of acceleration.

The general convention is to assume that the force units of thrust are kilonewtons, and the mass units are metric tons.

[filami]

Those equations represent ratios between those component so they work fine as long you keep consistency.

On the F=MA example:

if your mass is measured in kilos and you acceleration is measured in meters per second squared then your result is going to be in kg m/s2. If instead you measure mass in pounds, distances in miles and time in hours, then your result is going to be in pounds miles/hours2 The value is going to be different because the measurements are different but the real result is the same. You can convert those values just fine. Just keep in mind that the standard says that Newtons is kg m/s2 so if you want to present the result in standard form but you do the measurements using a non standard form, you have to make the conversions after you get the result.

I hope that was clear and I didnt say anything stupid (I am not a scientist =D

[rryy]

You can use different units as long as you change the other units to have the equation balanced. In F=ma, normally, F is in Newtons (N), m in kg, and a in m/s/s. If you want F to be in kN (1000*N), you would have to either make m in tonnes (1000*kg) or a km/s/s (1000*m/s/s), but not both. Either way, you are multiplying both parts of the equation by 1000.

[Epic DaVinci]

Thankyou Everyone, your replies helped a lot.